I'm at work, so I can't share any new screenshots right now, but I can tell you that the visual part of the theme works at least, I installed it last night. I'll try to check the bgm.bcstm file once I'm back home, but in YATA+ at least it played back without issues (Size is 1MB). Could it be that YATA+ ignores the 19kHz requirement? I downloaded it pre-converted from that brawl custom theme website since I didn't want to install some extra programs for the first theme, but it seems I may have to do the conversion process from scratch.Use a bgm.bcstm of 3.3mb or less that has been encoded using a base wav at 19000Hz or greater.
Set your theme to a default color one or no theme.
Install theme with CHMM or extdata.
Hit Y+Right to take a screenshot, then share it with us.